Numerous pathogenic microorganisms responsible for severe infections in humans and animals are resistant to the antibiotics currently used in clinical applications. The increasing development of microbial resistance is a major public health problem. Thus, during the past several years, there has been seen the development of considerable interest in the challenge of identifying new molecules, particularly for the study of short peptides 15 to 30 amino acids possessing antibacterial and antifungal activities—and having a mode of action different from the conventionally used antibiotics. Numerous peptides derived from human, animal and plant proteins are known to possess antimicrobial properties while others are generated synthetically on the basis of physicochemical studies.
The 14-mer linear peptide of sequence KLAKLAKKLAKLAK (SEQ ID NO: 4) was described in the literature as a nonhemolytic peptide having antibacterial activity (Javadpour MM, Juban, MM, Lo WC et al. De novo antimicrobial peptides with low mammalian cell toxicity. J Med Chem Aug. 2, 1996; 39(16): 3107-13). The limited studies carried out on that peptide showed activity against three strains of bacteria (E. coli, P. aeruginosa and S. aureus) during a short incubation period of 4 hours. Results with longer incubation periods have not been reported.